Methods and formulations using carbonic anhydrase and reaction compound combinations

ABSTRACT

Disclosed is a formulation for the absorption of CO 2 , which comprises water, at least one CO 2  absorption compound and a carbonic anhydrase as an activator to enhance the absorption capacity of the CO 2  absorption compound. The invention also concerns the use of carbonic anhydrase, in a CO 2  absorption solution to increase the CO 2  absorption rate of such solution.

INCORPORATION BY REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of application Ser. No.11/817,067, filed Aug. 24, 2007 now U.S. Pat. No. 7,740,689, which isthe national phase under 35 U.S.C. §371 of prior PCT InternationalApplication No. PCT/CA2006/000274 which has an International filing dateof Feb. 24, 2006, designating the United States of America, which claimsthe benefit of U.S. Provisional Patent Application No. 60/655,446, filedFeb. 24, 2005. The disclosures of prior applications including U.S.application Ser. No. 11/817,067, International Application No.PCT/CA2006/000274, and U.S. Provisional Patent Application No.60/655,446 are hereby expressly incorporated by reference in theirentirety and are hereby expressly made a portion of this application.

FIELD OF THE INVENTION

The present invention relates generally to solutions for absorbing CO₂for extraction and purification of gases. More particularly, it relatesto a CO₂ absorption solution containing a biocatalyst, namely carbonicanhydrase as an activator, to increase CO₂ absorption rate. It alsoconcerns the use of a biocatalyst, namely carbonic anhydrase, in a CO₂absorption solution to increase the CO₂ absorption rate of suchsolution.

BACKGROUND OF THE INVENTION

CO₂ removal from a gas stream may be obtained using chemical andphysical absorption processes. Chemical absorption of CO₂ may beperformed with amine based processes and alkaline salt-based processes.In such processes, the absorbing medium reacts with the absorbed CO₂.Amines may be primary, secondary, and tertiary. These groups differ intheir reaction rate, absorption capacity, corrosion, degradation, etc.In alkaline salt-based processes, the most popular absorption solutionshave been sodium and potassium carbonate. As compared to amines,alkaline salt solutions have lower reaction rates with CO₂.

Alkanolamines in aqueous solution are another class of absorbent liquidfor carbon dioxide removal from gaseous mixtures. Alkanolamines areclassified as primary, secondary, or tertiary depending on the number ofnon-hydrogen substituents bonded to the nitrogen atom of the aminogroup. Monoethanolamine (HOCH₂ CH₂NH₂) is an example of a well-knowprimary alkanolamine. Widely used secondary alkonalamine includediethanolamine ((HOCH₂CH₂)₂NH). Triethanolamine ((HOCH₂CH₂)₃N) andmethyldiethanolamine ((HOCH₂CH₂)₂NCH₃) are examples of tertiaryalkanolamines which have been used to absorb carbon dioxide fromindustrial gas mixtures. Molecular structures of sterically hinderedamines are generally similar to those of amines, except stericallyhindered amines have an amino group attached to a bulky alkyl group. Forexample, 2-amino-2-methyl-1-propanol (NH₂—C(CH₃)₂CH₂OH).

With primary and secondary alkanolamines (Pinola et al. Simulation ofpilot plant and industrial CO₂-MEA absorbers, Gas Separation &Purification, 7(1), 1993; Barth et al., Kinetics and mechanisms of thereactions of carbon dioxide with alkanolamines; A discussion concerningthe cases of MDEA and DEA, Chemical Engineering Science, 39(12),pp.1753-1757, 1984) the nitrogen reacts rapidly and directly with carbondioxide to bring the carbon dioxide into solution according to thefollowing reaction sequence:2 RNH₂+CO₂

RNHCOO⁻+RNH₃ ⁺  (1)

where R is an alkanol group. This reaction is the cornerstone of thepresent invention, as it is the one accelerated by carbonic anhydrase.The carbamate reaction product (RNHCOO⁻) must be hydrolysed tobicarbonate (HCO₃ ⁻) according to the following reaction:RNHCOO⁻+H₂O

RNH₂+HCO₃ ³¹   (2)

In forming a carbamate, primary and secondary alkanolamine undergo afast direct reaction with carbon dioxide which makes the rate of carbondioxide absorption rapid. In the case of primary and secondaryalkanolamines, formation of carbamate (reaction 1) is the main reactionwhile hydrolysis of carbamate (reaction 2) hardly takes place. This isdue to stability of the carbamate compound, which is caused byunrestricted rotation of the aliphatic carbon atom around theaminocarbamate group. According to U.S. Pat. No. 4,814,104 the overallreaction for the alkanolamines is written as:2 RNH₂+CO₂

RNHCOO⁻+RNH₃ ⁺  (3)

For the sterically hindered amines both reactions 1 and 2 play majorroles on the CO₂ absorption process. In contrast with the alkanolamines,the rotation of the bulky alkyl group around the aminocarbamate group isrestricted in sterically hindered amines. This results in considerablylow stability of the carbamate compound. The carbamate compound is thuslikely to react with water and forms free amine and bicarbonate ions(reaction 2). Due to the occurrence of reaction 2, only 1 mol of thesterically hindered amine instead of 2 mol of alkanolamine is requiredto react with 1 mol of CO₂. The overall reaction for sterically hinderedamines can be written as (Veawab et al., “ Influence of processparameters on corrosion behaviour in a sterically hindered amine-CO₂system”, Ind.Eng.Chem.Res., V 38, No. 1; 310-315; 1999; Park et al.,Effect of steric Hindrance on carbon Dioxide Absorption into New AmineSolutions: Thermodynamic and Spectroscopic Verification and NMRAnalysis, Environ. Science Technol. 37, pp.1670-1675, 2003; Xu, Kineticsof the reaction of carbon dioxide with 2-amino-2-methyl-1-propanolsolutions, Chemical Engineering Science, 51(6), pp.841-850, 1996):RNH₂+CO₂+H₂O

RNH₃+HCO₃ ⁻  (4)

Unlike primary and secondary alkanolamines, tertiary alkanolaminescannot react directly with carbon dioxide, because their amine reactionsite is fully substituted with substituent groups. Instead, carbondioxide is absorbed into solution by the following slow reaction withwater to form bicarbonate (U.S. Pat. No. 4,814,104; Ko, J. J. et al.,Kinetics of absorption of carbon dioxide into solutions ofN-methyldiethanolamine+water, Chemical Engineering Science, 55,pp.4139-4147, 2000; Crooks, J. E. et al., Kinetics of the reactionbetween carbon dioxide and tertiary amines, Journal of OrganicChemistry, 55(4),1372-1374, 1990; Rinker, E. B. et al., Kinetics andmodelling of carbon dioxide absorption into aqueous solutions ofN-methyldiethanolamine, Chemical Engineering Science, 50(5), pp.755-768,1995):R₃N+CO₂+H₂O

HCO₃ ⁻+R₃NH⁺  (5)

Physical absorption enables CO₂ to be physically absorbed in a solventaccording to Henry's law. Such absorption is temperature and pressuredependent. It is usually used at low temperature and high pressures.Typical solvents are dimethylether of polyethylene glycol and coldmethanol.

In recent years, a lot of effort has been put to develop new absorptionsolutions with enhanced CO₂ absorption performance. The use ofsterically hindered amines, including aminoethers, aminoalcohols,2-substituted piperidine alcohols and piperazine derivatives, insolution to remove carbon dioxide from acidic gases by scrubbing processwas the object of a patent in the late 1970 (U.S. Pat. No. 4,112,052).Yoshida et al. (U.S. Pat. No. 5,603,908) also used hindered amines toremove CO₂ from combustion gases, but mainly focused on reducing theenergy consumption from the amines regeneration. Fujii et al. (U.S. Pat.No. 6,274,108) used MEA in a process to absorb CO₂ from combustionexhaust gases, but were more concerned about the plant design, morespecifically storage of the amines and replenishing system. Instead ofusing amines, Suzuki et al. used various formulations of amino-amides toremove carbon dioxide from gases and absorbent (U.S. Pat. No.6,051,161).

In literature, some have reported new formulations of absorptionsolutions for chemical and physical processes. Reports exist about thereduction of corrosion of carbon steel with the use of certain aminecompounds (U.S. Pat. No. 6,689,332). These new formulations may implymixtures of amines (chemical solvent). For instance, patent U.S. Pat.No. 5,246,619 discloses a way of removing acid gases with a mixture ofsolvents comprising methyldiethanolamine and methylmonoethanolamine.Mixtures of dialkyl ethers of polyethylene glycol (physical solvent)(U.S. Pat. No. 6,203,599), and mixtures of chemical and physicalsolvents are reported. GB 1102943, for instance, reports a way ofremoving CO₂ by using a solution of an alkanolamine in a dialkyl etherof a polyalkylene glycol, while U.S. Pat. No. 6,602,443 reduces CO₂concentration from gas by adding tetraethylene glycol dimethyl ether incombination with other alkyl ethers of alkylene glycols. Although U.S.Pat. No. 6,071,484 describes ways to remove acid gas with independentultra-lean amines, mention is also made that a mixture of amines andphysical absorbents can also be used with similar results.

In order to increase the rate of CO₂ absorption, especially for aqueoustertiary alkanolamine solutions, promoters have been added to thesolutions. Promoters such as piperazine, N,N-diethyl hydroxylamine oraminoethylethanolamine (AEE), is added to an absorption solution(chemical or physical solvent). Yoshida et al. (U.S. Pat. No. 6,036,931)used various aminoalkylols in combination with either piperidine,piperazine, morpholine, glycine, 2-methylaminoethanol,2-piperidineethanol or 2-ethylaminoethanol. EP 0879631 discloses that aspecific piperazine derivative for liquid absorbent is remarkablyeffective for the removal of CO₂ from combustion gases. Peytavy et al.(U.S. Pat. No. 6,290,754) used methyldiethanolamine with an activator ofthe general formula H₂N—C_(n)H_(n)—NH—CH₂—CH₂OH, where n represents aninteger ranging from 1 to 4. U.S. Pat. No. 6,582,498 describes a wiresystem to reduce CO₂ from gases where absorbent amine solutions and thepresence of an activator are strongly suggested. U.S. Pat. No. 4,336,233relates to a process for removing CO₂ from gases by washing the gaseswith absorbents containing piperazine as an accelerator. Nieh (U.S. Pat.No. 4,696,803) relied on aqueous solution of N-methyldiethanolamine andN,N-diethyl hydroxylamine counter currently contacted with gases toremove CO₂ or other acid gases. Kubek et al (U.S. Pat. No. 4,814,104)found that the absorption of carbon dioxide from gas mixtures withaqueous absorbent solutions of tertiary alkanolamines is improved byincorporating at least one alkyleneamine promoter in the solution.

Other ways of enhancing CO₂ absorption involve ionic liquids, morespecifically a liquid comprising a cation and an anion having acarboxylate function (US 2005/0129598). Bmim-acetate and hmim-acetateare cited as examples.

Mention of enzyme utilization for gas extraction can also be found inthe literature (U.S. Pat. Nos. 6,143,556, 4,761,209, 4,602,987,3,910,780). Bonaventura et al. (U.S. Pat. No. 4,761,209) used carbonicanhydrase immobilized in a porous gel to remove CO₂ in an underwaterrebreathing apparatus. Carbonic anhydrase can also be used to impregnatemembranes used to facilitate CO₂ transfer into water for similarpurposes (U.S. Pat. Nos. 4,602,987, 3,910,780). Efforts were made toensure that the active site of the enzymes fixed on the membranes werein direct contact with the gas phase substrate to increase the activityof the enzymes (U.S. Pat. No. 6,143,556). This patent is the directcontinuation of patent U.S. Pat. No. 6,524,843, which claimed a way toremove CO₂ from gases with an enzyme, the carbonic anhydrase. This newpatent aims at improving the CO₂ absorption of the previous patentthrough the additional use of solvents, increasing the performance ofthe bioreactor.

CO₂ transformation may be catalyzed by a biocatalyst. The biocatalyst ispreferably the enzyme carbonic anhydrase. CO₂ transformation reaction isthe following:CO₂+H₂O

HCO₃ ³¹ +H⁺  (6)

Under optimum conditions, the turnover rate of this reaction may reach1×10⁶ molecules/second (Khalifah, R and Silverman D. N., Carbonicanhydrase kinetics and molecular function, The Carbonic Anhydrase,Plenum Press, New York, pp.49-64, 1991).

SUMMARY OF THE INVENTION

A first object of the present invention is to provide a CO₂ absorptionsolution with an increased CO₂ absorption rate.

In accordance with the present invention, that object is achieved with aformulation for absorbing CO₂ containing water, at least one CO₂absorption compound, and carbonic anhydrase as an activator to enhancethe absorption capacity of the CO₂ absorption compound.

A CO₂ absorption compound in accordance with the present inventionrepresents any compound known in the field which is capable to absorbgaseous CO₂.

Preferably, the CO₂ absorption compound is selected from the groupconsisting of amines, alkanolamines, dialkylether of polyalkyleneglycols and mixtures thereof.

By “amines” (as also in the term “alkanolamines”), it is meant anyoptionally substituted aliphatic or cyclic amines or diamines.

More preferably, the amines are selected from the group consisting ofpiperidine, piperazine and derivatives thereof which are substituted byat least one alkanol group.

By “alkanol”, as in the terms “alkanol group” or “alkanolamines”, it ismeant any optionally substituted alkyl group comprising at least onehydroxyl group.

Advantageously, the alkanolamines are selected from the group consistingof monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP),2-(2-aminoethylamino)ethanol (AEE),2-amino-2-hydroxymethyl-1,3-propanediol (Tris), N-methyldiethanolamine(MDEA) and triethanolamine.

The preferred dialkylether of polyalkylene glycols used according to theinvention are dialkylether of polyethylene glycols. Most preferably, adialkylether of polyethylene glycol is a dimethylether of polyethyleneglycol.

A second object of the invention is to provide a method to activate aCO₂ absorption solution, which comprises the steps of:

-   -   contacting gaseous CO₂ with an aqueous CO₂ absorption solution        containing at least one CO₂ absorption compound; and    -   adding carbonic anhydrase to said CO₂ absorption solution while        it is contacted with said gaseous CO₂.

Carbonic anhydrase is used as an activator to enhance performance ofabsorption solutions (for chemical/physical absorption) for CO₂ capture.

Thus, a third object of the invention concerns the use of carbonicanhydrase as an activator to increase CO₂ absorption rate in an aqueoussolution used for CO₂ absorption.

The enzyme may be one of the constituents of the absorption solution orit can be fixed to a solid substrate (support) such as packing materialonto which the absorption solution, in contact with gaseous CO₂, flows.

The objects, advantages and other features of the present invention willbe better understood upon reading of the following non-restrictivedescription of preferred embodiments thereof, given for the purpose ofexemplification only, with reference to the accompanying figures andexamples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents the performance, with or without using carbonicanhydrase, of absorption solutions comprising MEA, Tris, AMP, AEE, Pz orPEG DME as the CO₂ absorption compound; the performance is expressed asthe relative CO₂ transfer rate of the given solution to the CO₂ transferrate of a MEA solution without carbonic anhydrase, the concentration ofthe absorption solutions is 1.2×10⁻² M.

FIG. 2 represents the performance, with or without using carbonicanhydrase, of absorption solutions comprising MEA, AMP, MDEA or Tris asthe absorption compound; the performance is expressed as the relativeCO₂ transfer rate of the given solution to the CO₂ transfer rate of aMEA solution without carbonic anhydrase; the concentration of theabsorption solutions is 1.44×10⁻¹ M.

FIG. 3 represents the performance, with or without using carbonicanhydrase, of absorption solutions comprising MEA or AMP as theabsorption compound; the performance is expressed as the relative CO₂transfer rate of the given solution to the CO₂ transfer rate of a MEAsolution without carbonic anhydrase. the concentration of the absorptionsolutions is 0.87×10⁻¹ M.

DESCRIPTION OF PREFERRED EMBODIMENTS

The activation of an absorption solution by carbonic anhydrase may beobtained (1) by directly adding carbonic anhydrase to the absorptionsolution or (2) by contacting an absorption solution, in contact with agas phase containing CO₂, to a solid support having immobilized carbonicanhydrase.

Carbonic anhydrase enhances performance of absorption solutions byreacting with dissolved CO₂, maintaining a maximum CO₂ concentrationgradient between gas and liquid phases and then maximizing CO₂ transferrate.

The following examples present the two ways to activate absorptionsolutions with carbonic anhydrase.

EXAMPLE 1

An experiment was conducted in an absorption column. The absorptionsolution is an aqueous solution of2-amino-2-hydroxymethyl-1,3-propanediol (0.15% (w/w)). This absorptionsolution is contacted contercurrently with a gas phase with a CO₂concentration of 52,000 ppm. Liquid flow rate was 1.5 L/min and gas flowrate was 6.0 g/min. Gas and absorption solution were at roomtemperature. Operating pressure of the absorber was set at 5 psig. Thecolumn has a 7.5 cm diameter and a 70 cm height. Two tests wereperformed: the first with no activator, the second with carbonicanhydrase. The concentration of carbonic anhydrase is adjusted to 20 mgper liter of solution.

The results obtained showed that CO₂ removal rate is 1.5 time higher inthe absorption solution containing carbonic anhydrase. CO₂ transfer ratewas equal to 2.3× ⁻³ mol/min with carbonic anhydrase.

EXAMPLE 2

A gas, containing CO₂ at a concentration of 8% (v/v) is fed to a packedbed reactor containing immobilized carbonic anhydrase. The solidsubstrate is a polymeric material. The gas is countercurrently contactedto an aqueous absorption solution. Impact of the presence of theimmobilized enzyme, as an activator, has been tested for chemical andphysical solvents. Selected compounds for absorption solutions aremonoethanolamine (MEA), piperazine (Pz), 2-amino-2-methyl-1-propanol(AMP), 2-(2-aminoethylamino)ethanol (AEE),2-amino-2,hydroxymethyl-1,3-propanediol (Tris) and dimethyl ether ofpolyethylene glycol (PEG DME). Solutions were prepared at aconcentration of 1.2×10⁻² M.

Operating conditions were the following: gas flow rate is 3.0 g/min,absorption solution flow rate is 0.5 L/min. Height of packing withimmobilized enzyme 75 cm. Operating pressure is 1.4 psig.

Performance of absorption solutions are shown in FIG. 1. Performance isexpressed as a relative CO₂ transfer rate:

${Performance} = \frac{{CO}_{2}\mspace{14mu}{transfer}\mspace{14mu}{rate}\mspace{14mu}{of}\mspace{14mu} a\mspace{14mu}{given}\mspace{14mu}{solution}}{\begin{matrix}{{CO}_{2}\mspace{14mu}{transfer}\mspace{14mu}{rate}\mspace{14mu}{of}\mspace{14mu}{MEA}\mspace{14mu}{solution}\mspace{14mu}{without}} \\{{carbonic}\mspace{14mu}{anhydrase}}\end{matrix}}$

From FIG. 1, it can be observed that carbonic anhydrase enhanced the CO₂absorption of both chemical and physical absorption solutions.

EXAMPLE 3

A gas, containing 8% of CO₂ (v/v) is fed to a packed bed reactorcontaining immobilized carbonic anhydrase. The solid substrate is apolymeric material. The gas is countercurrently contacted to an aqueousabsorption solution. Selected compounds for absorption solutions aremonoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP),methyldiethanolamine (MDEA) and 2-amino-2,hydroxymethyl-1,3-propanediol(Tris). Solutions were prepared at a concentration of 1.44×10⁻¹ M.

Operating conditions were the following: gas flow rate is 1.0 g/min,absorption solution flow rate is 0.5 L/min. Height of packing is 25 cm.Operating pressure is 1.4 psig.

Performance of absorption solutions are shown in FIG. 2. Performance isexpressed as a relative CO₂ transfer rate:

${Performance} = \frac{{CO}_{2}\mspace{14mu}{transfer}\mspace{14mu}{rate}\mspace{14mu}{of}\mspace{14mu} a\mspace{14mu}{given}\mspace{14mu}{solution}}{\begin{matrix}{{CO}_{2}\mspace{14mu}{transfer}\mspace{14mu}{rate}\mspace{14mu}{of}\mspace{14mu}{MEA}\mspace{14mu}{solution}\mspace{14mu}{without}} \\{{carbonic}\mspace{14mu}{anhydrase}}\end{matrix}}$

From FIG. 2, it can be observed that carbonic anhydrase increased CO₂absorption for all solutions, except for the MEA solution. The absenceof increase between the test with and without enzyme is due to the factthat the efficiency of the MEA solution was of 100% under theseconditions. In this particular example, a relative transfer rate of 1equals to 100% CO₂ removal.

EXAMPLE 4

A gas, containing 8% of CO₂ (v/v) is fed to a packed bed reactorcontaining immobilized carbonic anhydrase. The solid substrate is apolymeric material. The gas is countercurrently contacted to an aqueousabsorption solution. Selected compounds for absorption solutions aremonoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP). Solutionswere prepared at a concentration of 87 mM.

Operating conditions were the following: gas flow rate is 3.0 g/min,absorption solution flow rate is 0.5 L/min. Height of packing is 25 cm.Operating pressure is 1.4 psig.

Performance of absorption solutions are shown in FIG. 3. Performance isexpressed as a relative CO₂ transfer rate:

${Performance} = \frac{{CO}_{2}\mspace{14mu}{transfer}\mspace{14mu}{rate}\mspace{14mu}{of}\mspace{14mu} a\mspace{14mu}{given}\mspace{14mu}{solution}}{\begin{matrix}{{CO}_{2}\mspace{14mu}{transfer}\mspace{14mu}{rate}\mspace{14mu}{of}\mspace{14mu}{MEA}\mspace{14mu}{solution}\mspace{14mu}{without}} \\{{carbonic}\mspace{14mu}{anhydrase}}\end{matrix}}$

It can clearly be seen that carbonic anhydrase increases the absorptioncapacity of absorption solutions . This increase can be obtained bothfor amine-based chemical absorption solutions and physical solutions.Reduced costs with lower need for solvents could thus be obtained.

Although preferred embodiments of the present invention have beendescribed in detail herein and illustrated in the accompanying drawings,it is to be understood that the invention is not limited to theseprecise embodiments and that various changes and modifications may beeffected therein without departing from the scope or spirit of thepresent invention.

What is claimed is:
 1. A formulation for CO₂ reactions comprising: (a) asolution comprising: (i) water; and (ii) at least one teritiary aminoreaction compound having the formula R₃N and enabling reaction (A):R₃N+CO₂+H₂O

HCO₃ ⁻+R₃NH⁺  (A); and (b) carbonic anhydrase to catalyze reaction (B):CO₂+H₂O

HCO₃+H⁺  (B).
 2. The formulation of claim 1, wherein the tertiary aminoreaction compound R₃N comprises a tertiary alkanolamine.
 3. Theformulation of claim 2, wherein the tertiary alkanolamine is selectedfrom triethanolamine (TEA) and N-methyldiethanolamine (MDEA).
 4. Theformulation of claim 1, wherein the carbonic anhydrase is directlypresent in and flows with the solution, is immobilized on a support, oris immobilized on a packing.
 5. A method for absorption of CO₂comprising contacting gaseous CO₂ with an aqueous CO₂ absorptionsolution comprising at least one CO₂ absorption compound and carbonicanhydrase wherein the carbonic anhydrase enables at least a 80% increasein CO₂ transfer rate relative to the same aqueous CO₂ absorptionsolution without the carbonic anhydrase.
 6. The method of claim 5,wherein the carbonic anhydrase is directly present in and flows with theaqueous CO₂ absorption solution, is immobilized on a support, or isimmobilized on a packing.
 7. A method to enhance CO₂ absorption,comprising providing carbonic anhydrase within a packed bed reactor;contacting gaseous CO₂ with an aqueous CO₂ absorption solutioncomprising at least one CO₂ absorption compound within the packed bedreactor in the presence of the carbonic anhydrase; and operating thepacked bed reactor to enable increased CO₂ transfer rate of at lest 80%relative to the same absorption solution without the carbonic anhydrase.8. The method of claim 7, wherein the carbonic anhydrase is directlypresent in and flows with the aqueous CO₂ absorption solution, isimmobilized on a support, or is immobilized on packing of the packed bedreactor.
 9. A formulation for absorption of CO₂ comprising water and atleast one CO₂ absorption compound comprising a carbonate salt, the waterand the at least one CO₂ absorption compound forming an alkalinecarbonate salt based solution; and carbonic anhydrase to enhance theabsorption of CO₂ into the alkaline carbonate salt based solution. 10.The formulation of claim 9, wherein the carbonate salt comprisespotassium carbonate or sodium carbonate.
 11. The formulation of claim 9,wherein the carbonic anhydrase is directly present in and flows with thealkaline carbonate salt based solution, is immobilized on a support, oris immobilized on a packing.
 12. A formulation for absorption of CO₂comprising water, at least one aliphatic CO₂ absorption compoundnon-reactive directly with CO₂, and carbonic anhydrase to enhance theabsorption of the CO₂ into the water.
 13. The formulation of claim 12,wherein the CO₂ absorption compound comprises an alkanolamine.
 14. Theformulation of claim 13, wherein the alkanolamine comprises a tertiaryalkanolamine.
 15. The formulation of claim 12, wherein the carbonicanhydrase is directly present in and flows with the water, isimmobilized on a support, or is immobilized on a packing.
 16. Aformulation for catalysis of the following reaction:CO₂+H₂O

HCO₃+H⁺ comprising water, at least one reaction compound selected fromcarbonates, sodium carbonate, potassium carbonate, alkyleneamines,=alkyl ethers of alkylene glycols, dimethylether of polyethylene glycol,tetraethylene glycol dimethyl ether, aminoethers, 2-substitutedpiperidine alcohols, piperazine, piperazine derivatives, ionic liquid, aliquid comprising a cation and an anion having a carboxylate function,and a combination thereof, the water and the at least one reactioncompound forming a solution; and carbonic anhydrase to catalyze thereaction.
 17. The formulation of claim 16, wherein the carbonicanhydrase is directly present in and flows with the solution, isimmobilized on a support, or is immobilized on a packing.
 18. A methodfor catalysis of the following reaction:CO₂+H₂O

HCO₃+H⁺ the method comprising providing a formulation comprising water;at least one reaction compound selected from carbonates, sodiumcarbonate, potassium carbonate, alkyleneamines, alkyl ethers of alkyleneglycols, dimethylether of polyethylene glycol, tetraethylene glycoldimethyl ether, aminoethers, 2-substituted piperidine alcohols,piperazine, piperazine derivatives, ionic liquid, a liquid comprising acation and an anion having a carboxylate function, and a combinationthereof, the water and the at least one reaction compound forming asolution; and carbonic anhydrase to catalyze the reaction.
 19. Themethod of claim 18, wherein the carbonic anhydrase is directly presentin and flows with the solution, is immobilized on a support, or isimmobilized on a packing.
 20. A formulation for catalysis of thefollowing reaction:CO₂+H₂O

HCO₃+H⁺ comprising water, at least one reaction compound comprising acation and an anion having a carboxylate function, the water and the atleast one reaction compound forming a solution; and carbonic anhydraseto catalyze the reaction.
 21. The formulation of claim 20, wherein thereaction compound comprising a cation and an anion having a carboxylatefunction is selected from bmim-acetate and hmim-acetate.
 22. The methodof claim 20, wherein the carbonic anhydrase is directly present in andflows with the solution, is immobilized on a support, or is immobilizedon a packing.